1. Field of the Invention
This invention relates to a building panel and to the method and apparatus for applying a coating to the building panel, and in particular to a building panel having a three-dimensionally patterned surface, which is enhanced in stereographic feeling through an application of shadow coating thereto. This invention also relates to a method and apparatus for applying a coating to such a three-dimensionally patterned surface of building panel.
2. Description of the Related Art
As shown in FIG. 17, in the case of a building panel 1 (inclusive of a plate, a board and the like which are usually employed as a building material) having a three-dimensional feature such as a tile-like pattern, a dark color coating is usually applied to the joint portions (groove portions) 3, i.e. the concave portions, while a light color is applied to the surfaces 70 of the convex portions (design portions) 4, whereby enhancing the stereographic feeling, i.e. by a difference in color between the convex portions 4 and the joint portions 3. As for the coating method to be typically employed in this case, a method is adopted wherein the entire surface of the building panel is coated at first in a dark color selected especially for the joint portions by means of spray method, and, after this coated layer is dried, the convex portions 4 are selectively coated in a light color by means of roller coating method.
Japanese Patent Publication H/6-98338 discloses a method of coating a building panel having a three-dimensionally patterned surface, wherein a spotty pattern is formed on the three-dimensionally patterned surface by jetting a coating material from a spray gun, thereby bringing about a color change between the concave portions and the convex portions.
Japanese Patent Publication H/7-22735 discloses a method of coating a building panel having a three-dimensionally patterned surface which is imitated to the surface of a natural stone, wherein a base coat, a first image coat, a second image coat and a top coat are successively applied to the three-dimensionally patterned surface, thereby obtaining a building panel having a surface of granite image.
Japanese Patent Unexamined Publication S/63-35471 discloses a method of coating a building panel having a three-dimensionally patterned tile-like surface, wherein the panel being moved on a conveyer is stopped moving for a while, during which a dark color paint is sprayed from four sides onto the surface of the panel, and after the coating of a light color paint is dried while continuously moving the conveyer, only the surface of convex portions of the panel is coated again with a light color paint by means of a roll coater.
Since the three-dimensionally patterned surface of building panel is simply coated by means of a spray gun or a roller coater according to the aforementioned conventional techniques, the sloped portions forming the concave (joint portion) is colored in the same color that is applied to the bottom portions of the concave portions. As a result, the color coated on the concave portions is made quite distinct from the color coated on the convex portions, thus failing to attain a natural stereographic feeling.
Namely, since a light color paint is coated only on the surfaces 70 of the convex portions 4, these surface portions 70 coated with light color appear as if they are covered respectively with a cap particularly when they are viewed perspectively. Therefore, these conventional coating methods explained above are incapable of attaining a natural stereographic feeling and are not preferable also in view of design.